Method and apparatus for forming spheres



Nov. 10, 1959 w. K. BECKWITH 2,911,669

METHOD AND APPARATUS FOR FORMING SPHERES Filed March 50, 1955 2Sheets-Sheet 1 wan/x1012 VIBRATOR FIG 3 V INVENTOR. WENDELL K; BECKWITHATTV.

W. K. BECKWITH METHOD AND APPARATUS FOR FORMING SPHERE IS Filed March30, 1955 2 Sheets-Sheet 2 BALL COOLED llallinl D. A H S L S S L m A m Na a M@ p s a m L F (Q a W w m o u R w i I 5 wm 5 L D 5 &m m UN 0 BALLmops:

cooL EaAl-L DQoP BALL TIMER: T\MER #z T|MER#3 TIMER *4 cuE ON FUEL ONOXYGEN ON FEED nouuuEL-|- Fuse. BALL FUEL ON FUEL ON OXYG EN 0N OXYGENON OXYGEN OFF AIR O AIR ON TO ROUNDEL INJECTOR INVENTOR. WENDELL K.BECKWITH VALVEfi O FUEL CONTROL VALVE.

United States Patent O A METHOD AND APPARATUS FOR FORMING SPHERESWendell K. Beckwith, Whitewater, Wis., assignor to The Parker PenCompany, Janesville, Win, a corporation of Wisconsin Application March39, 1955, Serial No. 497,980.

8 Claims: (Cl. 18-1) perfectly spherical in order to fit well in theball seat and to effectively apply a line to a writing surface.

I An object of the invention is to provide a method of forming spheresfrom fusible material whereby they are perfectly shaped.

.Another object is to provide a method of forming .spheresby fusion inwhich the pieces from which they are formed aresuspended in space duringtheir formation and thereafter until they are cooled sufiiciently toretain their shape resting on a solid supporting surface.

A further object is to provide a method of and apparatus for fusingspheres or balls in which the flame for fusing them is so shaped andcomposed that the piece being formed into a sphere is so maintained inthe flame that most efficient and perfect fusion is produced.

Still another object is to provide balls that are perfectly sphericaland can be pitted without losing their sphericity.

Another object is to provide a method of forming spheres that isunusually economical.

Still another object is to provide apparatus for forming spheres byfusion having construction for maintaining the pieces in the mosteffective part of the flame.

Other objects and advantages will appear from the following detaildescription taken in conjunction with the accompanying drawingsin whichFigure 1 is a vertical sectional view of a furnace em bodying principlesof the invention, and well adapted to carrying out the method of theinvention;

Figure 2 is an enlarged partial sectional View of the throat portion ofthe furnace;

Figure 3 is a view similar to Figure 2, but showing one of the elementsin an alternate adjusted position;

Figure 4 is a diagrammatic-schematic representation of the stages of thefusion of a ball;

Figure 5 illustrates various stages of a piece and the ball into whichit is formed;

Figure 6 is a diagrammatic representation of a timing arrangement forcontrolling the furnace; and

Figure 7 is a greatly enlarged sectional detail view of a ball fusedaccording to the present invention and later provided with a pittedsurface.

Referringin detail to the drawings, attention is directed first toFigures 1, 2 and 3 in which the furnace 12 includes a body portionhaving an upper part 14 and a lower part 16 suitably fitted together asin a telescopic ,arrangement and secured by a set screw 18. I Y Thelower part 16 includes a central bore or passage 20 extendingdownwardly, and is fitted with a receptacle 22 for receiving the balls24.

The halls merely drop into the receptacle 22 from a position in thefurnace in which they out portion of the insert. passage 50 in thefurnace body which communicates with I, Patented. Nov. 10, 1959.

are formed in the fusion process. Thefurnace is supported on a suitablesupport 26 upon which vibrators 28 of conventional form are mounted forvibrating the furnace and preventing the balls from adhering to thefurnace in the fusion process.

The upper part 14 is provided with a central bore 30 terminatingupwardly in a reduced portion 32, the latter opening into a bowl 34above it which diverges upwardly at a suitable angle for controlling theflame in which the balls are fused, as will be brought out later indetail. The throat of the furnace is where reduced portion 32 joins bowl34, and this is where the flame is controlled.

Fitted in the central bore 30 is an insert 36 having a flange 38 at itslower end clamped between mating surfaces of the parts 14 and 16 forsecuring the insert in place. A shim 40 is interposed between the flange38 and the upper part 14 for adjusting the upper part 14 upwardly andthereby effectively positioning insert 36 relative to the throat of thefurnace for controlling the character of the flame at thethroat of thefurnace. The shim 40 may be one of a series of shims of differentthicknesses. A shim is selected according to the relative position ofthe upper end of the insert 36 relative to the throat of the furnace.The upper end of the insert 36 has a reduced portion 42 extending intothe reduced portion 32 of the bore of the furnace.

The insert 36 has a central passage 44 for receiving air and oxygen, andthis passage opens upwardly into the bowl 34 and downwardly for droppingthe balls therethrough upon completion of the fusion process. Thepassage 44 is fed by radial passages 46 which in turn communicate withan annular space 43 formed by a cut- The passage 48 is fed by a aconduit 52 having branches for air and oxygen, the air branch beingdesignated 54 and the oxygen branch, 56.

These conduit branches are provided with suitable control 34. Thepassage 58 is fed by a passage 64 to which is connected a conduit 62 forproviding fuel to the furnace. .The conduit is provided, similarly tothe air and oxygen conduits, with suitable control valves :and apparatusfor supplying fuel to the furnace.

A chute 64 is disposed above the furnace bowl 34 for introducing piecesinto the furnace for forming the balls.

Associated with the chute 64 is suitable apparatus for introducing thepieces in timed relation to the other steps in the fusion process,namely, the supply of combustible gases, cooling air, dropping the fusedballs out of the furnace, etc.

A finished ball 24 is shown in each of Figures 2 and 3. The piece ormass from which the ball is formed, to begin with, is non-spherical orirregular as is, of course, understood in accordance with-the purpose ofthe invention. As explained above, the apparatus and method isparticularly adaptable to balls for use in ball point pens.

Sapphire and its equivalents are suitable materials for such balls;these materials are extremely hard, and they lend themselves to formingperfect spheres. As is well known, sapphire, natural or synthetic, ischemically the same or similar to aluminum oxide. Sapphire or themulti-crystal material known as corundum maybe used with equaleffectiveness in forming balls according to the invention. It will beunderstood also that other materials capable of being fused at practicaltemperatures in such furnaces may also be used, ruby being one of thematerials.

As an example, the balls may be formed from roundels cut from a rod;processes for performing this step are known. The rod is of a diametersimilar to, or perhaps slightly smaller than, that of the intendedsphere (which is in the neighborhood of 1 mm), and the roundel is cut tosuch length that its mass is that of the intended sphere, plus thatsmall amount lost by the tumbling operation, referred to hereinbelow,when such is utilized. The roundel as thus formed is shown at a inFigure and is of the shape generally of a short cylinder. One of theseroundels is deposited from the chute 64 into the furnace, as indicatedin Figure 1, by suitable feeding means which will feed one such roundelat the desired time in the cycle of fusion. The roundel is dropped ordeposited after establishment of the flame 66 (Figures 2 and 3) which isthe product of the fuel and oxygen delivered through the passages 44 and58. The flame is annular in shape, and it is so shaped and composed thatthe ball is maintained at that portion of the flame of the desiredtemperature for proper fusion. Sapphire fuses best at around 4000 F. andthe ball is maintained at the portion of the flame of approximately thattemperature. The piece or roundel is supported in the upstream of theflame by a well-known phenomenon and is thus suspended in space orsuspended in air (as the saying goes, although it is suspended by amixture of gases, the point being that it is not supported on a solidnon-yielding support). As a step preliminary to fusion, the corners orthe end edges of the roundel are slightly rounded to a short radius by atumbling operation preferably in water, over a period of a number ofhours. This is desirable so that such sharp corners are not overheatedas might otherwise be the case. Phase a of Figure 5 shows a roundelafter tumbling but before any fusion effect. Phase b shows the roundelor piece after 'partial fusion; the corners, although they have beenslightly rounded by the tumbling operation, are subjected to thegreatest heat and thus fuse faster than the other portions. This fusedportion at the corners is then drawn in more and more as the fusionoperation progrosses, and the piece approaches a spherical shape. Alater phase is shown at c in Figure 5 showing the corners more roundedbut the piece not yet a sphere. In the last phase d the piece is aperfectly rounded sphere. It might be here noted that the apparatus isso dimensioned relative to the intended dimension of sphere that thepassage 44 is only slightly larger than the completed sphere. Thepassage permits the sphere to drop there- 'through upon completion ofthe fusion and cooling operations, into the receptacle 22, as wasbrought out briefly above. Figure 7 shows a portion of a ball that hasbeen made spherical according to the present process, but afterwardsubjected to a pitting process for providing a pitted surface forcarrying ink from the ball seat to the writing surface. The method ofproviding the pitting is not an essential of the present invention andis referred to here for the purpose of pointing out the sphericity ofthe balls according to the process. The ball 24 of Figure 7 is formedwith a plurality of pits 68, but notwithstanding this, the surfaceportions 70 between the pits lie in a spherical surface formed anddetermined by the formation of the sphere according to the processoutlined above. It is in connection with a pitted ball that the hardnessof the material, such as sapphire or ruby, comes into prominence, in aball point pen. Sapphire, for example, is extremely hard and a sapphireball thus will not wear greatly when subjected to an abrading actionwith a ball seat formed of a softer material such as steel. Even wherethe seat is formed of glass, which is su than sapphire and does not havea great deleterious effect in abrading the sapphire ball. The same istrue of foreign particles that find their way between the ball and theseat. These particles, as is well known, cause a serious abrading effecton a ball of soft material, but since any such particles would be muchsofter than sapphire, they would not seriously affect sapphire. Hencethe pits remain in the surface.

As noted above, the sapphire must reach a substantial temperature tofuse, namely, in the neighborhood of 4000 F. It was found that in asolid flame issuing from a single passage the pieces did not reach theportion of the flame having the temperature necessary for fusion. Insuch a flame the hottest portion is in or near the center. The piecebounced above the flame or at the upper tip thereof and did not reachdown into the center where it was hot enough to fuse the material. Theannular type of flame formed by the apparatus of the present inventionenables the piece to lower into the flame where it is sufficiently hotto fuse it. The flame issuing from the throat of the furnace is annularin shape, and the roundel or piece is enabled to reach further down intothe flame while the flame is in full elfect. Figure 2 shows the portionsof the flame of the various temperatures. The portion where the ballrests is at approximately 4000 F. A neighboring portion outwardlyof thefirst may be 3500 F. Another portion deeper into the flame may be 4500R, which would be too hot for the fusion operation; and yet a fourthportion may be 2500 F. at the lowermost portion of the flame. The

stream of gases and flame is such as to support the ball as indicated inFigure 2, namely, at approximately 4000' F. The fuel, maintainedconstant, is delivered through the conduit 62 into the passage 58, andit then passes into the bowl 34 in an annular formation. The flame issupported by oxygen in the fusing operation, rather than by air, so asto produce a greater temperature. The oxygen is delivered through theconduit 56, 52 and into the passage 44 by suitable means, as wasexplained above.

The oxygen then issues upwardly from the passage 44 and combines withthe fuel at the throat in the bowl of the furnace, as indicated. Sincethe fuel is fed in in an annular pattern, the resulting flame is inannular form.

It is necessary that the pressure of the fuel and oxygen be maintainedwithin very close tolerances in order to flame issuing from the throatof the furnace. Obviously,

the heat would be greatly dissipated from the flame if the bowl were notpresent. The bowl, on the other hand, diverges upwardly so that theflame is permitted to expand as it rises, and a certain latitude ispermitted the piece or sphere to bob or bounce from side to sidesomewhat and still be supported in the proper portion of the flame. Thefurnace may be provided with suitable air cooling fins 72. Any tendencyfor the piece or roundel 24 to stick or adhere to the surface of thebowl 34 is obviated by the vibrators 28.

The upper end of the insert 36, namely, the portion 42 thereof, may beeffectively adjusted, as was pointed out above, by interposing a shim 40of different thick ness so as to position the insert variously withrespect to the lower end of the bowl 34. Such an adjustment is indicatedat Figure 3 in which the portion 42 terminates would be lowered somewhatin the throat so as to be more confined at the smaller portion of thebowl. Hence by such an adjustment as indicated, an additional controlstautially harder than steel, the glass is nevertheless softer of theheat of the flame may be attained. The flow of the gases or flame overthe edge of the juncture between the bowl and the bore is also of someimportance in the control of the flame.

' It is apparent from the foregoing that the sphere is completely formedwhile suspended in air, as contrasted with resting on a solid surface inwhich case a flat side may be formed. Thefusion of the sphere iscompleted while it is suspended. It is, of course, furthermore importantthat the sphere so formed be cooled and hardened sufliciently to preventforming a flat side before the sphere drops. This is accomplished byreplacing the oxygen with air, which is done after the fusion iscompleted and is preferably done gradually so as to stabilize the sphereor ball in the flame. In this step of the operation the air isintroduced in the air line shown and gradually increased in pressureuntil it surpasses the pressure of the oxygen and so backs up the oxygenin its line which is connected with the air line. The oxygen iseflectively cut off, but gradually so. The fuel is continued, however,and with the cessation of flow of oxygen, the. temperature of the flameis greatly reduced. The air which is injected is sufficient to maintainthe flame burning, but insufficient to retain the higher fusingtemperatures. The stream of air may be of any suitable pressure to coolthe ball and even raise it from the flame if desired. A ball need not becooled greatly in order for it to set or harden sufficiently to maintainits true sphericity when resting on a solid surface. After this isaccomplished, the air and oxygen are reduced and actually cut ofl, andthus the pressure of the stream of gases and the upstream force orstrength of the flame is materially reduced, and the ball drops by itsown weight through the passage 44 and into the receptacle 22. The balldrops through the flame, but the flame is lazy and incapable ofsupporting the ball or sphere. The flarne is maintained burning forconvenience in establishing the proper flame for the next cycle. Thecycle of operation is indicated in Figure 4, which is diagrammatic andschematic in nature. The cycle is composed of four stages, in the firststage the fuel and oxygen are on. The flame then quickly attains itsdesired heat and approximately half through the first period the roundel24 is injected. The flame and stream of gases is of suflicient upstreamforce to support the roundel. In the second period the flame cotninuesas it was at the end of the first period, and during this period theroundel changes shape and is completely formed into a sphere. Inthe'third period the air is turned on, While the fuel remains on, andthe oxygen replaced as described above, with the result that thetemperature of the flame drops materially, but the upstream force is notdecreased, and the rapid cooling action referred to takes place. At theend of the third period the air and oxygen are turned olf, and the upstream force of the flame becomes insufficient to support the sphere andthe sphere drops as indicated at the end of the schematic diagram. Thetemperature of the sphere when it drops is substantially below itsfusion point, and all danger of its becoming misshaped upon dropping iseliminated.

Figure 6 illustrates a schematic arrangement or device for controllingthe apparatus according to the steps or phases of Figure 4. A dial 74 isprovided with a hand 76 operated by a suitable clockwork. The dial isprovided with a plurality of sets of electrical contacts 78 arranged inpairs, and the hand 76 is provided with contact elements 80 arranged formaking contact between the contact strips of each pair when passing overthose strips. Leading from the contact strips are electrical wires 82connected to the respective controls such as roundel injector, fuelcontrol valve, etc. The diagram indicates that the fuel remains oncontinuously; the roundel injector is actuated approximately mid-way ofthe first period; the oxygen control valve is opened throughout thefirst three periods; and the air control valve is open during the thirdperiod. The lengths of the various periods are also indicated on thedial, the first being of three seconds, the second of four seconds,the-third of three seconds, and the fourth of two seconds. The completecycle is thus approximately twelve seconds. It will be understood thatthe form of control device may be as desired, and it is also desiredthat the lengths of the various periods may be adjusted withoutaffecting other periods, such as providing that certain periods mayoverlap somewhat, suitable controls being utilized for that purposewhich do not enter into the essence of the present invention.

One of the most important advantages of the invention is the change incrystal structure of the material of the balls. In the case of sapphireor other materials having single-crystal structure, it is virtuallyimpossible to pit the material and maintain its perfect sphericity. Forexample, in a conventional lapping operation, the effect is to producean out-of-roundness according to the orientation of the crystal axis.But the fusion process of this invention produces such a change in thecrystal structure that a uniform surface hardness is formed, and pittingcan be carried on without adversely affecting the sphericity. Thisphenomenon is also present in the case of pellets formed of aluminumoxide powder, which is of multi-crystal structure. The surface of ballsfused of this material is perfectly uniform and lends itself perfectlyto a pitting process.

It will be apparent from the foregoing that an unusually inexpensivemethod has been developed for producing spheres, in addition to havingthe advantage of forming perfect spheres.

I claim:

1. The method of forming a sphere from a piece of fusible material,comprising providing an upstream flame of controllably variabletemperature and upstream strength, suspending the piece in and by theflame stream until it is fused at least on its surface and the fusedmaterial flows to form a sphere of the piece, introducing a stream ofair into the flame stream thereby maintaining the strength of the streambut lowering the temperature for cooling the sphere to below its fusiontemperature while suspending it in the stream, and thereafterdiminishing the strength of the stream to allow the sphere to drop ontoa supporting surface.

2. The method of forming a sphere from a piece of fusible material,comprising, providing an upstream flame of annular form having a rootportion slightly larger in diameter than the sphere to he formed, saidflame being of controllably variable temperature and upstream force,introducing the piece into the flame, and controllably varying saidtemperature and force to suspend the piece in and by the flame streamuntil it is fused at least on its surface and the fused material flowsto form a sphere of the piece, to cool the piece while suspended, and tothereafter allow itto drop onto a supporting surface.

3. The method of claim 2 in which the piece is of sapphire or chemicalequivalent and the flame has portions of various temperatures and is soconstituted that the piece is maintained closely adjacent the region of4000 F. temperature.

4. The method of forming a sphere from a piece of fusible material,comprising providing an upwardly flowing stream of gases including anannular portion of fuel and a central portion of oxygen forming anannular flame at their confluence, suspending the piece in and by thestream until it is fused at least on its surface and the fused materialflows to form a sphere of the piece, thereafter replacing the oxygenwith air until the sphere is cooled below its fusion point and thendiminishing the strength of the stream and allowing the sphere to droponto a supporting surface.

5. Apparatus of the character disclosed, comprising a body having acentral vertical passage which opens at its upper end into a bowl, andwhich opens at its lower end into a collection receptacle, fuel conduitmeans leading into the bowl and having an annular opening there- "7 intoadjacent and surrounding the open upper end of the central passage,means for introducing acombustionsupporting gas into the bowl throughthe central passage, and means for controlling the force at which thegas is introduced and for controlling the degree to which the introducedgas supports combustion.

6. The invention of claim 5 in which the bowl of the body has anupwardly diverging conical wall leading upwardly from the upper end ofthe central passage.

7. Apparatus of the character disclosed, comprising a body having acentral vertical bore with an upper portion of reduced diameter andopening at its upper end into a bowl, an insert in the bore andcomplementally shaped therewith, said insert having a central verticalpassage which opens at its upper end into the bowl, and which opens atits lower end intoa collection receptacle, the upper end of said inserthaving clearance in the bore to form an annular passage between theinsert and the wall of the bore, which passage opens upward into thebowl annularly adjacent and surrounding the central vertical passage,means for adjusting the insert vertically to vary the size of theannularpassage between the insert and the wall of the bore, means forsupplying fuiel to the annular passage, means for supplying acombustionsupporting gas into the bowl through the centralpassage, andmeans for controlling the force at which the gas is introduced and forcontrolling the'degree to which the introduced gas supports combustion.p

8. The invention of claim 7 in which the bowl of the body has anupwardly diverging conical wall leading upwardly from the upper endofthe central passage.

References Cited the file of this patent UNITED STATES PATENTS Vogt Apr.,2l, 1936 Potters Dec. 2, 1952

